Plasmodium vivax is a protozoal parasite and a human pathogen. The most frequent and widely distributed cause of recurring (Benign tertian) malaria, P. vivax is one of the six species of malaria parasites that commonly infect humans.[1] It is less virulent than Plasmodium falciparum, the deadliest of the six, but vivax malaria can lead to severe disease and death.[2][3] P. vivax is carried by the female Anopheles mosquito, since it is only the female of the species that bite.